SEO when switching Domains?

Hey


I got this site, but the domain I wanted originally was parked and selling for an arm and a leg. I purchased a different domain, thinking I will make money, and be able to afford the good domain. If I am successful with domain B and want to buy domain A, is that like founding a whole other site? Can I make it so the site is now at Domain B? How will this affect my backlinks and already built SEO with Domain B once I decide to switch to A? Can someone describe the best course of action with this process?

A simple 301 redirect will transfer all link juice to the site. Best to 301 each page to the new page instead of all to the new index page though.

When Domains switch to SEO than site gonna top.